The use of bundling ties to bundle a plurality of elongate objects such as electrical wires or cables has long been known. One early example of such a bundling tie is shown in U.S. Pat. No. 3,102,311. Typically, bundling ties include a strap which may be looped around a bundle of articles and secured in a head portion which locks the strap thereto.
Locking mechanisms used in bundling ties basically take two forms. One approach has been the use of integrally formed locking means pivotally carried by the head of the tie. Such locking means includes a toothed plastic pawl which engages corresponding teeth on the tail of the strap. Advantages of locking means of this type are readily apparent in that the strap can be integrally molded with no secondary operation needed for providing the locking means. An example of such a bundling tie is shown and described in U.S. Pat. No. 3,486,201. One distinct disadvantage of a tie of this construction is that it requires intricate molding techniques to form the tie. Both the pawl and the tail must include complimentary ratchet teeth thereon for locking purposes. Deformation of the interlocking plastic teeth could cause undesirable pullout of the tail from the tie head. Also, the teeth and the tail form stress points which weaken the tie and could cause undesired breakage.
A second technique for forming locking means in a bundling tie head includes the use of a metallic barb embedded into the base of the tie head at an angle to the inserted tail. This provides a self-clinching device which bites into the tail of the tie to securely retain the strap in the head. An example of a bundling tie having a metallic barb is shown and described in U.S. Pat. No. 3,186,047. The metal barb of the tie of the '047 patent actually bites into the inserted tail. Thus, there is no need to provide complimentary teeth on the tail as is necessary with the device of the '201 patent. The biting engagement of the metal barb into the tail portion of the strap provides superior pullout resistance and results in a smooth body tail which has superior strength. However, since locking engagement of the head and the tail is achieved by the metal barb actually digging into the strap, there could be a tendency for the metallic barb to dig too deeply into the strap, thus weakening the strap at the point of engagement. It is therefore desirable to provide a barb for a bundling tie head which will limit the depth of insertion of the barb into the strap, thereby preventing the severing of the strap thereat and increasing tensile and shear strength of the tie.